Changing the review policy to approve with single +2

We do not have much active contributors in patrole now and waiting
for second +2 is time taking and end up not merging the patches.

let's change the patch merge policy to require only single +2.

Once we have enough contributors then we can change it back to two +2.

Change-Id: I60d5e4ac559511d59088f1a9f06ca2022eabd609
diff --git a/REVIEWING.rst b/REVIEWING.rst
index 9993f2c..f8ea144 100644
--- a/REVIEWING.rst
+++ b/REVIEWING.rst
@@ -181,8 +181,9 @@
 
 When to approve
 ---------------
-* Every patch needs two +2's before being approved.
+* Every patch can be approved with single +2 which means single reviewer can approve.
 * It's OK to hold off on an approval until a subject matter expert reviews it.
 * If a patch has already been approved but requires a trivial rebase to merge,
-  you do not have to wait for a second +2, since the patch has already had
-  two +2's.
+  you do not have to wait for a +2, since the patch has already had +2's. With
+  single +2 rule, this means that author can also approve this case if he/she has
+  approve rights.